Battery branch and commissioning specification — revision 1
Open the interactive workbench, select LiPo commissioning, then Place the resistors. The measurement form accepts your real readings, checks simple consistency, saves a local session, and exports JSON or a printable record. The animation is not an electrical simulator and cannot detect a miswired circuit.
Build scope: one supervised, unloaded MG996R powered from one 3S pack; XIAO ESP32-S3 powered separately by USB. This is a concrete bench design awaiting physical commissioning. It is not released for unattended use or qualified as a complete production camera node. The release requirements below state exactly what remains.
Confirmed hardware and limits
| Item | Confirmed information | Design consequence |
|---|---|---|
| Gens Ace GEA223S30X6GT | User reports two packs; each 2200 mAh, 11.1 V / 3S, 30C, XT60 main, JST-XHR balance; 168 g, 106 × 34 × 21 mm | Use one pack at a time; full-charge voltage is 12.6 V. Label packs A and B. |
| Botland LM2596, product 2967 | Seller specifies 3.2–35 V input, up to 2 A without a heatsink and 3 A with cooling | Voltage range covers the pack. Output current, cooling, startup and transients still need actual testing. |
| MG996R | User's seller specification: 4.8–6.0 V, 500 mA operating current, 0–180°; stall/startup current not supplied | Set the servo rail to 5.0 V. Do not use the 500 mA figure as a worst-case current budget or apply 6.6 V from another variant's specification. |
| SkyRC iMAX B6 V2 | Charger owned; external DC adapter not confirmed | Verify its 11–18 V input supply and connectors before charging or using DC-output mode. |
| Capacitors | 470 µF / 25 V low-ESR pack; additional 1000 µF / 25 V, five pieces | Start with one 470 µF near the servo. 1000 µF is an alternative after retesting startup/inrush; do not add all capacitors indiscriminately. |
| 200-piece resistor assortment | Owned; individual values, tolerance and power ratings not stated | Check for 220 Ω, 10 kΩ and 1 kΩ at the specified ratings. Do not assume it includes a 10 W load resistor. |
| 3.3↔5 V level-converter module | Owned; exact circuit unidentified | Verify topology, direction, timing, supply sequencing and logic thresholds before using it for servo control. It is not a power converter. |
The seller's thermal/current conditions are from the exact Botland listing. The low-end input description is not a reason to operate near dropout; this design uses the 3S range. The TI IC specification is not a complete qualification of the assembled module.
Power wiring: terminal-to-terminal netlist
Naming: D2 is the SB540 reverse-polarity diode. The MVP guide uses D1 for the 1N5819 diode in front of the XIAO 5V pin.
Build the mating harness while completely disconnected from the battery. Use short 18 AWG main supply/return leads and properly rated, insulated connectors; retain the servo's verified original lead. Keep all motor power and raw battery conductors off the breadboard. Every newly added harness component must be suitable for the fuse current, temperature, and fault duty.
ONE 3S PACK
XT60 positive
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TP1 (insulated access on mating harness)
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F1 3 A / 32 V DC MINI fuse example, in a matching holder near the pack
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S1 verified DC-rated disconnect, e.g. at least 5 A at 24 V DC
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D2 SB540: anode toward S1; BANDED CATHODE toward converter
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TP2 -------------------------------- LM2596 IN+
XT60 negative -------------------------- LM2596 IN−
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TP0 -------------------------------- LM2596 OUT− --- direct return --- TP0S
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USB-powered XIAO GND -----------------------+ servo GND
LM2596 OUT+ ------- TP3 ------- direct +5 V harness ------- TP4 -------- servo +
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+------------+-----------+
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C1 + lead R3 1 kΩ
470 µF / 25 V 0.25 W
C1 − lead |
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TP0S ---------------------+
XIAO D0 / GPIO1 ---- R1 220 Ω ----+------------------------------ servo signal
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R2 10 kΩ
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XIAO GND / common return
XIAO power: USB only. XIAO 3V3 is TP5; it is not a battery input.
TP0 and TP0S are the same electrical return but different physical measurement locations. Probe TP4 against TP0S to include wiring drop at the servo connector. Verify common IN−/OUT− on the actual disconnected converter. A crossing on the drawing is not an electrical junction unless the conductors meet at a named node.
F1 is provisional for this single-servo bench branch. Confirm normal input current and inrush against the fuse time-current curve and the least-rated harness component. It is not the final fuse selection for two motors plus a camera. The Littelfuse 297 MINI series includes a 3 A / 32 V DC example; its stated interrupting rating is 1000 A at 32 V DC. Use a matching genuine part/holder and verify suitability for the assembly.
D2's band marks its cathode. The Vishay SB540 is a candidate 40 V / 5 A axial Schottky rectifier. Its continuous capability is thermally dependent. At input current I and forward drop Vf it dissipates approximately I × Vf watts; inspect temperature under the actual load. This is a series reverse-polarity element, not a diode across the battery or across the complete servo supply.
F1 does not clamp voltage. D2 does not stop a converter overvoltage failure. Neither provides per-cell battery cutoff. Do not intentionally connect the LiPo backward or short it to demonstrate these protections.
Resistor schedule and exact example holes
Use unused breadboard rows 20, 22, and 24, with the verified a–e connected groups. No motor power flows through these groups.
| Reference | Value / minimum nominal power | Placement | Purpose |
|---|---|---|---|
| R1 | 220 Ω / 0.25 W | XIAO D0 → a20; resistor b20 → b22; e22 → servo signal | Modest signal series resistance; not a voltage regulator or guaranteed fault protection |
| R2 | 10 kΩ / 0.25 W | Resistor c22 → c24; XIAO GND → a24; share this reference with servo return | Pulls the servo-side signal low when GPIO is high-impedance |
| R3 | 1 kΩ / 0.25 W | Direct harness TP4 → TP0S, parallel with C1, outside breadboard motor-current routing | Bleeds charge from the output capacitor after shutdown |
| R4 | 10 Ω / 10 W, suitable power-resistor construction/mounting | Temporarily TP3 → TP0 with electronics disconnected | Normal-load commissioning test; remove before connecting a servo |
Check resistor values with all power removed; measuring a resistor in-circuit can give a lower reading due to parallel paths. R1/R2 nominally produce 3.3 × 10000 / 10220 ≈ 3.23 V at a high signal level. Verify compatibility with your actual servo. A pull-down does not guarantee every servo stays motionless on power-up. If a logic buffer is needed, qualify the purchased level-converter first; its presence alone does not establish suitability.
At 5 V, R3 draws 5 mA and dissipates 0.025 W. With only 470 µF, its ideal RC time constant is 0.47 s; with 1000 µF it is 1 s. The converter's own capacitance and other connected parts change discharge time. Always measure below 0.1 V before rewiring.
At 5 V, R4 draws 0.5 A and dissipates 2.5 W. A 0.25 W resistor from the kit is unsuitable. Follow the 10 W resistor's cooling/mounting instructions, keep it away from plastic and fingers, and let it cool before removal. This test is not a stall-current test. Never use a resistor network as a substitute for a regulated 5 V motor supply.
The existing sensor boards may already contain I²C pull-ups. Measure/inspect their arrangement before adding more. LEDs require their own series resistor; the optional LED assortment is outside this battery power path.
Meter test points and criteria
Black lead in COM, red in the voltage/resistance socket, meter in DC volts. “Within window” means only that one manually entered value meets the bench criterion. It does not establish complete safety or transient behavior.
| Point / condition | Black probe | Red probe | Bench criterion |
|---|---|---|---|
| TP1, pack isolated from load | TP0 | TP1 | 10.5–12.6 V before these supervised tests |
| CELL1–3 | Use verified P309/charger display; no adjacent-pin probing | Record each individual cell | Each 3.5–4.2 V; spread ≤0.10 V; sum agrees with TP1 within 0.10 V |
| TP2, input enabled | TP0 | Diode cathode / IN+ | TP1 minus diode and wiring drop; investigate >0.8 V loss at this bench stage |
| TP3, no servo or R4 attached | TP0 / OUT− | OUT+ | Adjust to 4.9–5.1 V |
| LOAD, R4 attached | TP0 / OUT− | TP3 | 4.8–5.2 V at about 0.5 A |
| TP4, one unloaded servo moving | TP0S, at servo | Servo positive | 4.8–5.2 V; also observe resets, heating and movement |
| TP5, XIAO on USB | XIAO GND | XIAO 3V3 | 3.2–3.4 V screening window |
| OFF, all sources unplugged | TP0S | TP4 | Below 0.1 V before rewiring |
The pack/cell lower bounds and spread criteria are conservative pre-test choices, not the pack's absolute discharge limits or a battery-health diagnosis. An in-range total can hide an imbalanced cell. Stop and investigate disagreement between instruments. Use a cell alarm during operation and disconnect at the alarm; a 3.5 V/cell early bench warning is an example if the P309 supports it. Never leave an alarm-only setup unattended.
A handheld DMM will not necessarily capture startup overshoot or short servo-induced dips. An oscilloscope or suitable transient recorder, realistic loads, and temperature measurements are needed for supply qualification. Never interpret an average voltage reading on the servo signal wire as proof of valid PWM pulses.
Use the B6 V2 you already own
The B6 V2 requires an 11–18 V DC adapter. Verify the adapter and cable before use. For this standard 3S LiPo, select LiPo BALANCE, 3S / 11.1 V, and 4.20 V/cell termination. 2.2 A = 1C for 2200 mAh; use that setting only if permitted by the pack instructions, and follow any lower limit. The 30C discharge specification is not a charge rate. Connect XT60 and JST-XHR using the manual's polarity/orientation, confirm both selected and detected cell counts are 3S, and charge with the prototype disconnected, attended on a suitable nonflammable surface. Do not select LiHV. Official B6 V2 manual, charging sections
The charger also has a DC/DC output mode. With its proper input adapter and no battery connected to its output/balance port, it can supply normal bench loads. An example is 9 V / 1 A into the LM2596 test harness. Verify mode and actual output first, and stop output before changing connections. This is not a battery charging program. The manufacturer's stated DC-output range is 5–26 V, 1–6 A, with a 60 W maximum; do not mistake that output range for the 11–18 V input range. Its startup/current-limiting behavior is not qualified by this guide; use a suitable lab source for fault qualification. SkyRC B6 V2 product specification
Commission in this order
- Verify exact component variants, connectors, fuse/holder, switch DC rating, resistor ratings, and diode orientation. Inspect the disconnected harness for shorts. Do not populate it while attached to a LiPo.
- Qualify the converter from the bench source with no electronics connected: adjust output, power-cycle, then perform the temporary R4 load test. Remove R4 after powering off and discharge/cooling.
- With S1 off, replace the bench source with the pack. Verify pack cells, TP1, TP2 and unloaded TP3. Do not leave any connection that ties the bench source and battery together.
- Unplug the pack and USB; verify discharge; fit C1, R3, the direct servo power harness, common ground, R1 and R2.
- Power XIAO by USB; verify TP5 and load the manual test. With horn removed, connect the pack and enable the servo branch. Measure TP4 during small movements; stop on abnormal behavior.
- Stop movement, switch off, unplug pack and USB, remove the cell monitor, and record OFF. Export your results. Recheck after any rewiring rather than carrying results forward.
Requirements for a production hardware release
| Open item | Required evidence or implementation |
|---|---|
| Output overvoltage protection | A qualified cutoff/clamp design that prevents damaging output reaching the loads, including converter fail-high and startup behavior; an input fuse is insufficient |
| Per-cell undervoltage protection | A correctly designed and tested 3S cell-monitor/cutoff path compatible with the separate balance charger; total-voltage software or P309 alone is insufficient |
| Two-axis power | Actual combined worst-case current, motor start/stop behavior, connector drop, cooling, and regulator transient/load qualification; 500 mA per servo is not a worst-case figure |
| Logic/camera branch | Separate adequately rated regulated branch; verify each board's input and a safe USB/external-power selection path before removing USB |
| USB power path | No parallel positive sources or backfeeding a computer; follow the XIAO power guidance and verify the chosen implementation |
| Motor fault behavior | Calibrated travel limits, bounded command handling, timeout behavior, safe startup, and a physical power disconnect; define how gravity-loaded tilt is supported when power is removed |
| Mechanical assembly | Fit, cable strain relief, keyed/insulated connectors, cooling clearances, gear/travel checks, and wiring documentation for the actual build |
| Qualification | Recorded worst-case load, supply transitions, temperature, runtime, and protection tests using controlled sources/fixtures; no deliberate destructive LiPo tests |
Protection components require a designed circuit and qualified ratings; a generic “protection module” listing is not sufficient evidence. TI distinguishes overvoltage, overcurrent, reverse polarity, reverse current and inrush functions in its power-path protection overview. Follow Seeed's XIAO power documentation for any later external-power path.
The optional OLED, temperature sensor, and level converter could support a later diagnostics interface after their exact module variants are identified. They are not wired into this first battery branch. This keeps the wiring and the measurements aligned with the circuit actually under test.